The invention relates to a device for fastening an axle with rolling bearings in a cylindrical tubing comprising two annular sleeves having inward extensions for locking up the outer races of the rolling bearings with fastening members for relatively fixing the sleeves in place and with an outward shoulder at the end remote from the fastening members. Such a device, which may be employed for mounting the crank axle in a bicycle frame, is known from German Patent Application No. 2,647,289 and it comprises in the embodiment shown therein two sleeves having external screwthread to engage a frame tubing having internal screwthread. In order to move the sleeves to the correct locations they are each provided with a set nut and the distance between the two sleeves is determined by a length of tube. Mounting an axle by means of such a device in a circuitous and time-consuming operation. During the course of time while the axle is mounted the sleeves may become loose so that the assembly will exhibit an amount of play.